If you've been following the story of comet 3I/ATLAS since its discovery on 1 July 2025, you'll know that the story has been a bit of a rollercoaster.
From the initial excitement of learning that this amazing object is an interstellar visitor, having formed beyond our Solar System, to its disappearance behind the Sun in autumn 2025 and its re-emergence into the winter morning sky, it's been amazing to watch the story of 3I/ATLAS develop.
We've even had claims that 3I/ATLAS is an alien spacecraft (a notion, we should point out, that the vast, vast majority of professional astronomers passionately refute).
And we've had amazing images of 3I/ATLAS captured by just about every ground-based and space-based telescope, including the Gemini South telescope, the Very Large Telescope, the Hubble Space Telescope and the James Webb Space Telescope.
We've seen images of 3I/ATLAS captured by solar-observing spacecraft, by missions at Mars and even by a spacecraft on its way to Jupiter.
This Friday, 19 December, the story reaches another milestone, as 3I/ATLAS is due to make its closest approach to Earth.
The comet's close approach and how to watch online
On Friday, the interstellar comet – which is temporarily passing through our Solar System – will get closer to Earth than it's been so far.
The caveat, though, is that this 'close approach' is still nearly twice the distance between Earth and the Sun. That's about 270 million km away, or 170 million miles, according to NASA.
Nevertheless, this cometary milestone is sure to be recorded and captured by professional astronomers using humanity's best telescopes. But also, we hope, by amateur astronomers and astrophotographers from their back gardens.
That's right: it is possible to see comet 3I/ATLAS in the sky using amateur equipment such as smart telescopes.
You can find out how to do this in our regular comet chaser Stuart Atkinson's blog on how to see comet 3I/ATLAS, and his guide on how to photograph 3I/ATLAS.
Stuart has been following the comet for us for a few weeks now, braving the cold mornings in Cumbria, UK, to keep an eye on this interstellar visitor.
If you don't have the means to observe 3I/ATLAS yourself, or fancy staying indoors with a cup of something hot instead, the folks over at the Virtual Telescope Project have announced they will be live-streaming the comet's close approach.
That means you can get a view of the comet from the comfort of your bed, on your smartphone or tablet.
You can watch 3I/ATLAS's close approach to Earth via the livestream below.
If you do manage to get out and capture an image of 3I/ATLAS, please send us your images and they could feature in an upcoming issue of BBC Sky at Night Magazine.
Fingers crossed for clear skies tomorrow!
